Spacing and ribbon feed mechanism for typewriters



United States Patent [72] Inventor Rentaro Sasaki Takasaki, Japan [21]Appl. No. 710,894 [22] Filed March 6, 1968 Continuation-impart of Ser.No. 498,659, Oct. 20, 1965, now abandoned. [45] Patented Oct. 6, 1970[73] Assignee Oki Electric Industry Company Limited Minato-ku, Tokyo,Japan [32] Priority Nov. 25, 1964, Dec. 26, 1964 [33] Japan [31]39/90785 and 39/100213 [54] SPACING AND RIBBON FEED MECHANISM FORTYPEWRITERS 4 Claims, 9 Drawing Figs.

[52] US. Cl 197/48, 197/82, 197/151, 197/165 [51} 1nt.C1 B41j1/32, B41j19/00, B41j 33/44 [50] Field ofSearch 197/1, 16,

[56] References Cited UNlTED STATES PATENTS 3,184,028 5/1965Kleinschmidtetal 197/161 859,732 7/1907 Birch 1 197/160 1,690,48711/1928 H0110 197/151 2,701,045 2 1955 Nl 197/68X 2,742,132 4/1956Anderson H 197/160 2,757,775 8/1956 Hickerson 197/49 2,769,029 10/1956Hw 197/49X 2,879,876 3/1959 Palmer et a1 197/16 2,902,136 9/1959 Whippo197/165 2,905,302 9/1959 Hickerson 197/52 2,978,086 4/1961 Hickerson197/16 3,042,174 7/1962 Howard 197/55X Primary Examiner- Ernest T.Wright, Jr. Altorney-McGlew and Toren ABSTRACT: A subassembly for atypewriter includes a type unit mounted for shifting along a shaftoperable to oscillate the unit. The unit includes a known rotatable andaxially shiftable type head. A ribbon mechanism is disengageably mountedon the unit for operative association with the type head, and includesmanual and automatic means for reversing the direction of ribbon feed. Aspacing mechanism, of the cable and spring drum type, inc1udesselectively operable means whereby the type unit may be shiftedlaterally a substantial distance, for observing the typing, withautomatic return ofthe type unit to the proper typing position.

Patented Oct. 6, 1970 Sheet INVENTOR REA! TARO ,S'ASA KI Patented Oct.6, 1970 Sheet 2, of4

INVENTOR RENTARO SASAKI ATTORNEYS F l6 3c INVENTOR REM TARO 51354ATTORNEYS Patented Oct. 6, 1970 I 3,532,204

INVENTOR REN 74 R0 54 SA KI ATTORNEYS SPACING AND RIBBON FEED MECHANISMFOR TYPEWRITERS CROSS REFERENCE TO RELATED APPLICATION This applicationis a continuation-in-part of application Ser. No. 498,659, filed Oct.20, 1965, for Typing Device for Typewriters, now abandoned.

BACKGROUND OF THE INVENTION In conventional typewriters, such as thatshown in US. Pat. No. 2,757,775, a part ofa typing mechanism and aribbon are separated or lowered from a platen, so that letters typed onpaper on the platen may be viewed. The operation of known devices foreffecting this is complicated to such an extent that difficulties areexperienced with either the typing mechanism or the ribbon feedingmechanism. Also, in conventional typewriters, the ribbon mechanism isnot detachable as a unit from the typing device or type unit, but isfixed relative to the typing device or unit.

SUMMARY OF THE INVENTION This invention relates to typewriters and, moreparticularly, to a novel and improved type unit spacer mechanism and anovel and improved ribbon mechanism for typewriters.

In accordance with the invention, the spacer mechanism is a cable-typespacer mechanism including a pair of cables each having one end attachedto a typing unit which is slidable along an oscillatable bar. The cablesare trained around respective pulleys located at opposite ends of thepath of movement of the typing unit. The opposite end of one cable isattached to a spring wound drum, and the opposite end of the other cableis attached to a ratchet-type mechanism operable by the keys and spacerbar to step" the typing unit along the platen.

The principal feature of this spacer mechanism in accordance with theinvention is the provision of a double groove pulley positionedintermediate the ends of the path of movement of the typing unit androtatably mounted at the free end of a lever arm. One cable is trainedaround one groove of this pulley before passing to the spring wounddrum, and the other cable is trained around the other groove of thepulley before passing to the ratchet mechanism. A spring biases thedouble groove pulley to a first or normal position.

' A cam is associated with the pivoted lever mounting the double groovepulley. When it is desired to move the typing unit laterally to view aline of type, an operating member is actuated and the cam is turned toswing the pulley mounting lever against the spring bias. This causes adecrease in the length of one cable extending between the double groovepulley and the typing unit. Correspondingly, there is effected anincrease in the length of the other cable extending between the doublegroove pulley and the ratchet mechanism. As a result, the typing unit isdisplaced by a preset distance laterally, so that the line of type maybe viewed. Upon release of the cam operating member, the spring biasesthe double groove pulley back to its initial position with return of thetyping unit to the position it occupied before being shifted laterallyfor viewing ofa line of typing.

The operation of the spacing mechanism and of the ribbon feed iseffected by oscillation of the shaft mounting the typing unit, and thisshaft, during its oscillation, oscillates canis controlling the ratchetdevice for the spacing mechanism and cams controlling the ribbon feed. Amanual ribbon feed reversing lever is provided and is operable to effectsetting of pawls, associated with ratchets, to feed the ribbon in eitherone direction or the other direction. Furthermore, a lever is providedhaving a forked end through which the ribbon extends between the tworibbon reels and, adjacent either end of the ribbon, a rivet is securedto the ribbon. When this rivet engages the forked cnd of the mentionedlever, it oscillates the lever and this effects, through interconnectedlevers, reversal of the direction of ribbon feed, by disengaging thefeed for one direction and engaging the feed for the other direction.The entire ribbon feed mechanism is a unit which is arranged to bemounted on the typing unit, with the ribbon being fed in a loop aroundguide means operatively associated with the rotatable and axiallydisplaceable typing head.

An object of the invention is to provide a typing head spacingmechanism, for moving a typing unit supporting the typing head parallelto a platen, and wherein the unit can, at any time, be shifted laterallythrough a predetermined distance to provide for viewing of the typedcharacters.

Another object of the invention is to provide such an arrangement inwhich the typing unit not only supports an axially and anguarlydisplaceable typing [head but also supports a unit comprising the ribbonfeed mechanism.

A further object of the invention is to provide such an arrangementwhich is simple, reliable, and easy to operate.

Still another object of the invention is to provide a compact ribbonmechanism including a ribbon feeding mechanism which can be eithermanually or automatically changed as to direction of feed.

A further object of the invention is to provide such a compact ribbonmechanism which is disengageably mountable as a unit in the typing unit.

Yet, another object of the invention is to provide such a ribbonmechanism in which it is easy to replace the ribbon, and which is simpleto handle.

BRIEF DESCRIPTION OF THE DRAWING For an understanding of the principlesof the invention, reference is made to the following description of atypical embodiment thereof as illustrated in the accompanying drawing.

In the drawing:

FIG, 1 is a somewhat schematic perspective view of a typing unit, ribbonunit and typing unit spacer mechanism embodying the invention;

FIG. 2 is a perspective view of the ribbon mechanism unit, with thetyping unit being shown in phantom;

FIG. 3A is a perspective view of a portion of the ribbon mechanism, asdisassembled:

FIG. 3B is a perspective view of another portion of the ribbonmechanism, as disassembled;

FIG. 3C is a partial perspective view illustrating part of the means forautomatically reversing the direction of ribbon feed as the ribbonapproaches a condition in which it is substantially completely unwoundfrom one reel or the other;

FIG. 4 is a perspective view ofa ribbon feed reversing lever;

FIG. 5 is a perspective view illustrating the relation between theribbon feed reversing lever and the ribbon feed ratchet means shown inFIGS. 3A and 3B; and

FIGS. 6 and 7 are somewhat schematic and exploded perspective viewsillustrating the operation of the ribbon feed reversing mechanism as theribbon nears its right end and nears its left end, respectively.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring first to FIG. 1, atypewriter is partially illustrated as including the usual platen I onwhich there is positioned a paper 2 to be typed. A typing mechanism orunit is illustrated at 3 as comprising a known type of angularly andaxially displaceable typing head 4, a ribbon feed mechanism 5 and acarrier 6. Carrier 6 for the typing unit 3 is mounted slidably on ashaft 7 which is oscillatable as indicated by the arrow. As stated,typing head 4 is mounted on carrier 6 for displacement b'oth axially andangularly. Ribbon mechanism 5 is disengageably inserted into the carrier6, in a manner described more fully hereinafter, and moved therewithalong shaft 7.

The spacing mechanism for stepping carrier 6 along shaft 7 1 comprisestwo cables 8a and 8b, each having an end secured to carrier 6. Thesecables 8a and 8b may be in the form of ropes, chords or wires. Cable 8ahas one end 103 fixedly secured to the left side of carrier 6, as viewedin FIG. 1, and then extends around a pulley 29 and around one groove ofa double groove pulley 13, with the opposite end of cable 8a beingsecured to a spring wound drum 9. Cable 8b has one end 104 secured tothe right side of carrier 6, as viewed in FIG. 1, and then extendsaround a pulley 30 and around the other groove of double groove pulley13, with the opposite end of cable 8b being connected to a drum 10 fixedto rotate with a ratchet 11 having operatively associated therewithpawls 14 and spring biased by respective springs 14a and 15a to engagethe teeth of ratchet 11. The pulleys 29 and 30 are rotatably mounted ateach end of the path of travel of carrier 6 along shaft 7.

Double groove pulley 13 is rotatably mounted, at 27, on the free end ofa lever 12 which is pivoted to a fixed portion of the typewriter at 26and is spring biased, by a spring 24, into engagement with a cam 25fixed to a shaft 28. The levers 14 and 15 are reciprocated, relative toratchet 11, by respective cams 16 secured to a shaft 17, with the levers14 and 15 operating in alternation on ratchet 11 so that one lever 14will move the ratchet 11 in one angular direction while the other lever15 restrains reverse rotation of the ratchet 11, the two levers 14 I and15 reversing functions on the next operation of cams 16.

Spring drum 9 is constantly biased to rotate in a counterclockwisedirection so as to maintain tension on cable 8a and bias carrier 6 tothe left as viewed in FIG. 1. The shaft 17 carrying the cams 16 isoscillated, in a known manner, by operation of a typewriter key or byoperation of the typewriter space bar. The operation of the pawls l4 and15 steps carrier 6 to the right as viewed in FIG. 1 responsive to eachkey or space bar operation. To effect the typing, the ribbon mechanismincludes a ribbon 31 which is wound on one spool 32 while being unwoundfrom a spool 34 (FIG. 2) or vice versa, and the ribbon 31 extends aroundthe typing head 4. In the usual manner common with typewriters employingrotatable and axially displaceable typing heads, such as the typing head4, shaft 7 is oscillated, each time a key or a space bar of thetypewriter is depressed, to oscillate carrier 6. Through knownmechanism, oscillation of shaft 7 effects oscillation of shaft 17, andalso effects oscillation of other cams to be described hereinafter,likewise in a known manner and through the use of known intermediatemechanism. Such mechanisms are shown, for example, in US. Pat. No.2,879,876 and US. Pat. No. 2,978,086.

When it is necessary or desirable to inspect a portion of a line oftyping on the paper 2, shaft 28 is angularly displaced, by suitablemanual or automatically operable means connected thereto, to rotate cam25 to swing lever 12 counterclockwise from the position illustrated insolid lines in FIG. 1 to the position illustrated in phantom in FIG. 1.This movement is effected against the bias of spring 24. As a result ofthe swinging of lever or arm 12, double grooved pulley I3 is displacedto the left to the position illustrated in phantom in FIG. 1. Thiseffects a drawing of cable 8b, and a corresponding release of cable 8a,so that carriage or support 6 is moved to the right from the positionillustrated in solid lines to the position illustrated in phantom, thusallowing a portion of a typed line to be viewed. After the typed linehas been reviewed, shaft 28 is manually rotated back to the positionillustrated in solid lines and spring 24, maintaining arm 12 in contactwith cam 25, swings arm 12 clockwise thus moving double grooved pulley13 back to its previous position. The momentary displacement of thetyping unit 3, for viewing of a portion of a typed line, has nodisturbing effect on the subsequent spacing and typing operations,inasmuch as the typing unit 3 is returned to exactly its originalposition.

Referring to FIG. 2, a ribbon mechanism frame 20, preferably formed of ahard light material, such as a suitable synthetic resin, comprises aunit in which the elements shown in solid lines in FIG. 2 are suitablymounted and housed. Frame is detachably mounted on carrier 6 in anysuitable manner such as, for example, by inserting its legs 20b intorecesses 100 in carrier 6. Frame 20 can be readily removed from carrier6 by withdrawing legs 201) from the recesses 100.

The ribbon mechanism will be described in detail with particularreference to FIGS. 2 through 7. Of these figures, FIG. 2 is aperspective view of the ribbon mechanism as a whole, illustrating themeans for shifting or reversing the feeding of ribbon 31. Ribbon 31 issecured to a lefthand spool 32 and a righthand spool 34, and is arrangedto be unwound from one spool while being wound on the other, and viceversa, so that the ribbon 31 can be used repeatedly. Spools 32 and 34are removably mounted on shafts 39a and 40a, respectively, of respectiveratchets 39 and 40, the spools 32, 34 being maintained on theirrespective shafts 39a, 40a by suitable means such as, for example,pivoted fingers 80 of which one is shown in FIG. 2. Also in the usualmanner, each spool 32 and 34, when mounted on a shaft 39a or 40a, isfixed against rotation relative to its mounting shaft 39a, 400, as bysuitable key means.

In accordance with the present invention, the forward feed and reversefeed can be shifted or interchanged either manually or automatically,and the manual shifting mechanism will be explained first. Againreferring to FIG. 2, a ribbon feed reversing lever 33, also illustratedin FIGS. 3A and 5 and, in somewhat greater detail, in FIG. 4, is fixedto a pivot shaft 18 which is rotatably supported in the housing or frame20. An end 19 of lever 33 projects through an opening 20a of the ribbonmechanism frame or unit 20, as shown in FIG. 2, whereby lever 33 can beoperated manually. Lever 33 is a twoarm lever, including an arm 33afixedly extending at an angle from the arm carrying the manual operatingpart 19. Arm 33a has its outer end formed with a cam part 35 for forwardfeed of ribbon 31 and a cam part 36 for reverse feed of ribbon 31, thecam parts 35 and 36 being in vertically spaced relation to each other asparticularly shown in FIG. 4. Referring to FIGS. 2 and 3A, 3B and 3C, areverse feed pawl 37 is illustrated, more particularly in FIG. 3A, as atwo-arm lever pivoted on a pivot 72. One arm of lever 37 is connected toa tension spring 57 which biases lever 37 to swing counterclockwise sothat the opposite end of the other arm of lever 37 will be engaged withreverse feed ratchet 39 whenever a lug or abutment 21 on this arm oflever 37 is out of contact with the ribbon forward feed cam 35 of lever33. Similarly, a forward feed pawl 38 is illustrated as a two-arm leverpivoted on a pivot 73, and having a tension spring 58 secured to theouter end of one arm and biasing lever 38 to swing counterclockwise. Theouter end of the other arm of lever 38 is engaged with a forward feedratchet 40 whenever an abutment 22 on this arm is not engaged by thereverse feed cam 36.

Referring to FIG. 5, a check pawl 60 is pivoted at 74 and is springbiased by a tension spring 62 so that its operative end will remain inengagement with reverse feed ratchet 39 as long as a projecting pin 64rides on the lower stepped part 68 Ofd cam 66 forming a fixed part oflever 33 and operable to control pawl 60. Another check pawl 61 ispivoted at and spring biased by a tension spring 63 to engage forwardfeed ratchet 40. A pin 65 projects to the left from pawl 61, inopposition to the direction of projection of pin 64, and is arranged toengage either the lower stepped part 68 of cam 66 or a higher steppedpart 69 thereof. When engaged with the lower stepped part 68 of cam 66,pin 65 provides for pawl 61 to operatively engage ratchet 40. Similarly,when pawl 60 has its pin 64 engaged with a higher stepped part 67 of cam66, pawl 60 is lifted out of engagement with ratchet 39.

A ribbon feed cam 54, best seen in FIG. 3B, and a ribbon reversing cam47, best seen in FIG. 3A, are slidably mounted on shaft 7 but are fixedagainst rotation relative to this shaft 7. It should be noted, at thispoint, that intermediate its ends, ribbon 31 extends over guide rollers70 and 71.

Referring again to FIG. 38, a cam follower lever 56 is pivotally mountedat 76 and is spring biased to rotate counterclockwise by a tensionspring 59. Lever 56 has an end 56a of one arm continuously engaged withcam 54 under the bias of spring 59. The lever 56 has a pair ofadditional arms 56b, arranged in spaced parallel relation, and each ofthese arms has an upwardly offset portion 56' or 56" to which theopposite end of a tension spring 57 or 58, respectively, is secured.Pawl 37 is pivoted to one arm 56b at 72, and pawl 38 is pivoted to theother arm 56b by pivot 73. The ends of springs 57 and 58, respectively,are connected to the outer ends 37' and 38', respectively, of therespective pawls 37 and 38.

The operation of those parts of the ribbon mechanism mentioned thus farwill now be described. Operation of the typing keys or of the space baroscillates shaft 7 in the direction indicated by the arrow. This causeslever 56 to rotate in a clockwise direction so that ribbon reverse feedpawl 37, engaged with reverse feed ratchet 39, rotates this ratchet 39clockwise with reverse rotation of ratchet 39 being prevented by checkpawl 60. Thus, the left-hand spool 32 is rotated in a clockwisedirection so that ribbon 31 is fed in the direction indicated by thesolid line arrow in FIG. 3A. At this time, feed pawl 38 is disengagedfrom ratchet 40 and check pawl 61 is also disengaged from this ratchet40.

To change the direction of feed of ribbon 31 to that indicated by thebroken line arrow in FIG. 3A, ribbon feed reversing lever 33 is manuallydisplaced in a clockwise direction as indicated by the solid arrow inFIG. 3A. By virtue of such movement of lever 33, forward feed cam 35 atthe outer end of arm 33a of lever 33 engages lug 21 of feed pawl 37 topivot feed pawl 37 clockwise so that its operative end is disengagedfrom reverse feed ratchet 39. By virtue of this movement of lever 33,reverse cam 36 of lever 33 is disengaged from lug 22 of forward feedpawl 38, so that the latter can swing counterclockwise under theinfluence of spring 58, to engage forward feed ratchet 40. At the sametime, pin 64 moves from stepped surface portion 68 onto the raisedstepped portion 67, so that check pawl 60 is disengaged from reversefeed ratchet 39. correspondingly, pin 65 moves from raised steppedportion 69 of cam 66 onto the lower stepped portion 68, so that checkpawl 61 is moved into operative engagement with forward feed ratchet 40under the bias of spring 63.

Consequently. by pivoting lever 33 clockwise, feed pawl 37 and checkpawl 60 are effectively disengaged from ratchet 39, and feed pawl 38 andcheck pawl 61 are efiectively brought into operative association withratchet 40, so that the direction of feed of ribbon 31 is reversed sothat right-hand ribbon spool 34 is rotated clockwise step-by-step uponeach operation of a typewriter key or typewriter space bar.

Automatic reversal of the ribbon feed is effected in a manner which willnow be described. Referring to FIG. 3C, when that portion of ribbon 31wound on left-hand spool 32 is almost entirely unwound therefrom, aneyelet 41 anchored in ribbon 31, will engage the bifurcated arm 43 of aleft ribbon end lever 42, the spacing between the bifurcations of member43 being just sufficient for ribbon 31 to pass therethrough withoutengagement therewith, but insufficient for eyelet 41 to passtherethrough. When eyelet 41 engages member 43, lever 42 will be rotatedcounterclockwise about a shaft 44, against the bias of a spring 102, asbest seen in FIG. 6. Lever 42 includes an arm 42a which is articulated,by a link 42b, to the upper end of a left hook lever 45. Consequently,lever 45 will be swung clockwise from the solid line position of FIG. 6tothe phantom position of FIG. 6. This will bring the notched lower endof lever 45 above a plate 46 forming part of a ribbon reversing camlever 49. A spring 48 biases lever 49 in a counterclockwise direction tomaintain an end 49a thereof in engagement with cam 47 fixed to oscillatewith shaft 7. The cam 47 will thus oscillate lever 49 including plateportion 46.

During each oscillation of lever 49, hook lever 45, whose notched end isnow engaged over plate portion 46, will be lifted by plate 46. A pin 50,pivotally mounting hook lever 45, is connected to arm 33a of feedreversing lever 33. Consequently, during an upward movement of hooklever 45, feed reversing lever 33 will be swung counterclockwise toshift the direction of ribbon feed in the manner already explained withrespect to manual shifting of the ribbon feed. This causes ribbon 31 tobe fed in the reverse direction as indicated by the solid line arrow inFIG. 3A.

Referring now to FIGS. 2 and 7, when ribbon 31 is nearly completelyunwound from right-hand spool 34, an eyelet 41 secured to ribbon 31 nearthis end of the ribbon 31 will engage a bifurcated member 52 of a rightribbon end lever 51 also pivoted on the shaft 44. This will pivot lever51 counterclockwise, against the bias ofa spring 101, so that its arm51a,

articulated by a link 51b to a right hook lever 53, will swing,

lever 53 clockwise from the solid line position of FIG. 7 in thedirection of the arrow therein to the phantom position of FIG. 7. Due tothe aforementioned oscillation of lever 49 and plate 46, the plate 46,during clockwise movement thereof, will engage a hook end 53', broughtbeneath the plate 46 by swinging of lever 53, and pull hook lever 53downwardly. Hook lever 53 is pivoted on a pin 55 secured to arm 33a offeed reversing lever 33. Thus, feed reversing lever 33 will be swungclockwise and, in the manner described above for manual operation, willagain reverse the direction of ribbon feed so that the ribbon 31 will befed in the direction indicated by the broken line arrow of FIG. 3A.

I claim:

1. In a typewriter of the type including a platen and a typing unitmounted adjacent the platen for movement parallel to the axis of thelatter, the typing unit including a type head and a ribbon cooperabletherewith, and spacer mechanism connected to the typing unit andoperable, responsive to selective actuation of the typewriter keys andspace bar, to step the typing unit in a direction parallel to the axisof the platen, the spacer mechanism including a cable secured to thetyping unit and having its ends connected to indexing pulley means, theimprovement comprising, in combination, selectively operable typing unitshifting means operatively associated with said cable intermediate theends thereof and selectively operable on said cable, when actuated andwhen said typing unit is in an indexed position, to draw said cable,with said indexing pulley means remaining stationary, to move saidtyping unit through a preselected number of indexing steps from saidindexed position, to expose typed matter on a paper on said platen; saidshifting means, when released, effecting return of said typing unit tosaid indexed position; ribbon feed mechanism on said typing unit andoperatively associated with said ribbon; said ribbon feed mechanismcomprising a mechanism supporting frame having a pair of depending legs;said typing unit being formed with a pair of recesses removablyreceiving said depending legs whereby said ribbozn feed mechanism may bedisengageably mounted as a unit on said typing unit.

2. In a typewriter of the type including a platen and a typing unitmounted adjacent the platen for movement parallel to the axis of thelatter, the typing unit including a type head and a ribbon cooperabletherewith, and spacer mechanism connected to the typing unit andoperable, responsive to selective actuation of the typewriter keys andspace bar, to step the typing unit in a direction parallel to the axisof the platen, the spacer mechanism including a cable secured to thetyping unit and having its ends connected to indexing pulley means, theimprovement comprising, in combination, selectively operable typing unitshifting means operatively associated with said cable intermediate theends thereof and selectively operable on said cable, when actuated andwhen said typing unit is in an indexed position, to draw said cable,with said indexing pulley means remaining stationary, to move saidtyping unit through a preselected number of indexing steps from saidindexed position, to expose typed matter on a paper on said platen; saidshifting means, when released, effecting return of said typing unit tosaid indexed position; ribbon feed mechanism on said typing unit andoperatively associated with said ribbon; said indexing pulley meanscomprising a pair of spring wound drums each having a respective end ofthe cable secured thereto; said shifting means comprising a doublegroove pulley intermediate said spring wound drums and having the end ofthe cable extending to each spring wound drum extending around arespective groove as a bight in the cable, the two bights facing inopposite directions, a lever pivotally mounted on the typewriter frameand rotatably supporting said double groove pulley at its free end, andmeans selectively operable to swing said lever in a direction toincrease the length of cable between said double groove pulley and onespring wound drum with a corresponding and equal decrease in the lengthof the cable between said double groove pulley and the other springwound drum.

3. In a typewriter, the improvement claimed in claim 2, ineluding a pairof further pulleys each interposed between said double groove pulley anda point of fixation of said cable and having said cable trainedtherearound to reverse the cable direction.

4. ln a typewriter of the type including a platen and a typing unitmounted adjacent the platen for movement parallel to the axis of thelatter, the typing unit including a type head and a ribbon cooperabletherewith, and spacer mechanism connected to the typing unit andoperable, responsive to selective actuation of the typewriter keys andspace bar, to step the typing unit in a direction parallel to the axisof the platen, the spacer mechanism including a cable secured to thetyping unit and having its ends connected to indexing pulley means, theimprovement comprising, in combination, selectively operable typing unitshifting means operatively associated with said cable intermediatethe-ends thereof and selectively operable on said cable, when actuatedand when said typing unit is in an indexed position, to draw said cable,with said indexing pulley means remaining stationary, to move saidtyping unit through a preselected number of indexing steps from saidindexed position, to expose typed matter on a paper on said platen; saidshifting means, when released, effecting return of said typing unit tosaid indexed position; ribbon feed mechanism on said typing unit andoperatively associated with said ribbon; said ribbon feed mechanismcomprising a pair of ribbon spools having said ribbon wound thereof forextending between said type head and said platen; respective ratchetseach fixed to rotate with a respective ribbon spool; respective pawls,each associated with a respective ratchet, and operated, responsive totyping and spacing operations on the typewriter, to advance theassociated ratchet step-by-step; cam lever means operable to maintainone pawl retracted from its associated ratchet while providing for theother pawl to remain in operative engagement with its associatedratchet; manually operable selector means connected to said cam levermeans to operate the latter to select the direction of ribbon feed;ribbon feed reversing means connected to said cam lever means andoperable by the ribbon as the latter is substantially fully unwound fromone ribbon spool and substantially fully wound on the other ribbonspool, to actuate said cam lever means to reverse the direction ofribbon feed; said cam lever means comprising one arm of a two-arm camlever, the other arm of said two-arm cam lever being formed for manualoperation; means pivotally mounting said two-arm cam lever; respectivecam means on the free end of said one arm each engageable with arespective pawl to retract the same from operative engagement with itsassociated ratchet responsive to movement of the other arm of saidtwo-arm cam lever in a selected direction; said feed direction reversingmeans comprising a second pivotally mounted two-arm lever oscillatedresponsive to typing and spacing operations on the typewriter, a pair ofpivotally mounted second levers each having a forked end through whichthe ribbon extends and engageable by abutment means on the ribbonadjacent each end thereof, and a respective stop articulated to eachrespective second lever and normally retained by the latter out ofoperative relation with said second two-arm lever; each second lever,responsive to swinging thereof by an abutment on the ribbon, moving itsassociated stop into the path of oscillation of said second twoarmlever; and means on each stop engageable with said twoarm cam lever toswing the same to reverse the direction of ribbon feed.

